This invention relates to a hand covering for controlling electrostatic discharges, specifically by grounding an operator in an electrostatic environment.
Naphtha and methyl ethyl ketone are organic solvents used in automotive painting. To prevent operators from coming into skin contact with these solvents, it is necessary for them to wear some form of chemically resistant hand covering. Traditionally, such hand covering has been gloves made from acrylonitrile-butadiene co-polymers, commonly called nitrile rubber. Nitrile rubber provides good resistance to chemicals used in automotive paint lines. The gloves are generally seamless to prevent any solvent from seeping in. However, cut and sewn polyvinyl chloride gloves are sometimes used when contact with organic solvents is minimal.
In electrostatic painting, the object to be painted is negatively charged while the paint and paint spray dispenser are positively charged. The paint droplets are attracted to the negatively charged object just as the north pole of a magnet is attracted to the south pole of another magnet. This gives even coverage of paint and minimizes waste.
However, if the operator is wearing a glove made of a material which is relatively nonconductive, such as nitrile rubber, it prevents the operator from being adequately grounded and some paint may fly back toward the operator. To prevent this, it is necessary to ground the operator, preferably without sacrificing the operator""s protection from the paint solvents.
Various grounding devices have been proposed for a variety of reasons. For example, U.S. Pat. No. 3,596,134 teaches the protection of persons from electrical discharge in electrostatic fields by means of foot sandals, belt, and gloves all interconnected by conductive leads. This ensemble is used to disperse electrical charges concentrated in particular parts of the person""s body. The construction of such a glove includes an outer surface of leather with a conductive lining on the inside so that the accumulated charge in the hand area is removed through the inner conductive lining, through the lead to ground. In this configuration, the charge has to pass through the insulative material, such as leather, to the inner lining which presents a substantially high resistive path.
U.S. Pat. No. 5,704,066 teaches the grounding of persons handling spark plug wires by means of a metal mesh glove attached to the metal frame work of the automobile by a conductive wire and alligator clip. Although this structure eliminates the danger of electric shock, it does not fulfill the need for improved protection against skin absorption and skin contact with toxic chemicals or solvents. Also, it is cumbersome to operate and is not cost effective for electrostatic painting.
U.S. Pat. No. 5,855,301 teaches electrostatic grounding for manually operated fluid dispensers, in which an operator is grounded by means of a conductive glove. The glove is made from a synthetic rubber such as Nitrilite from Ansell-Edmont Industrial Inc. of Coshocton, Ohio and which has a resistance of 108 to 1011 ohms. Although this glove is used in conjunction with a wrist band, this combination by no means provides an easy path for the electric charge, and is cumbersome in operation.
Accordingly, it is an object of this invention to provide a cost-effective solution to controlling electrostatic discharge by providing a conductive path away from a charged object to ground.
It is also an object of the invention to provide a structure with a protective material to mitigate skin contact with toxic chemicals, including aqueous solutions and organic solvents, wherein such a material has a low permeation rate with a high fluid breakthrough time.
A hand covering in the form of a glove is provided for protecting an operator from solvents used in automotive painting while grounding the operator. This is accomplished by applying conductive tape to a finished glove. The tape is secured to the outer surface of the glove, positioned on the palm side of the glove and extends down the cuff or gauntlet, around to the inside of the glove, back up the cuff or gauntlet to the inside palm of the glove. This allows an electrical charge to be transferred from the paint spray dispenser to the palm of the glove and then to the operator, thereby grounding the operator.
The tape can be applied using a solvent resistant adhesive such as the acrylic adhesive on Scotch(trademark) Electrical Tape 1194. It should be noted that the adhesive can be non-conductive. A variety of gloves can be used, provided that the outer surface is solvent resistant and the tape can be firmly attached.